Manufactured first in 1856, the side-hammer,
cap-and-ball Colt model 1855 rifle operated on principles similar to Colt’s
revolving handguns. 100 colt rifles were purchased and sent to the U.S.
troops for field service in 1857. The pre-war .44 caliber rifles were
six-shot repeaters, while the war-time procurement guns were .56-caliber five
shots. The barrel length of the U.S. Army Colt rifles ranged from 31 5/16
“ to 37 ˝ “, and the full length fore-arm was attached to the barrel by
two barrel bands. The rear sight was graduated up to 600 yards, and the
top straps of the .56-caliber wartime-made guns were stamped, “ COL. COLT’
HARTFORD CT. U.S.A.” The cylinders were fluted, and the rifle took either
the angular or saber bayonet. Prior to 1861, the Army had taken delivery
of more than 700 model 1855 Colts.

In May 1861, a company of
the 8th Massachusetts Infantry was issued Colt revolving rifles while serving in
and around Washington, D.C. Later in 1861, pickets of the 12th Kentucky Infantry
skirmished with Confederate cavalry at Mill Springs, Ky. The pickets, armed with
Colt rifles, killed four rebels with eight shots at 300 yds.

At the end of January 1862,
Washington Arsenal took delivery of 1,000 ,56-cal. Colt Model 1855 revolving
rifles with 37 ˝ “ barrels, and they were issued to Berdan's 1st and 2nd U.S.
Sharpshooters (U.S.S.S.).

When the sharpshooters were informed of the matter,
the men rioted. They had been promised Sharps rifles, and they wanted the
Sharps— no other arm would do. Berdan had to place a guard around his
headquarters until the excitement subsided. One man of the 2nd Sharpshooters was
so dissatisfied he marched off to war with a Springfield rifle-musket. The
sharpshooters left for the front with the Colts and some individual target
rifles. The 1st U.S.S.S. used Colts in the Siege at Yorktown against Rebel
artillery batteries, while the 2nd U.S.S.S. fought against Confederate infantry
and artillery at Falmouth, Va. The Colts were exchanged for the promised Sharps
by early June, and, in August 1862, the Washington Arsenal had 445 of Berdan's
Colts in storage.

One of the largest issues of
Colt revolving rifles in 1863 went to the 21st Ohio Infantry. On May 28,1863,
the regiment turned in its 350 Enfield rifle-muskets for a like quantity of
.56-cal., five-shot Colts. The 21st's rifles had been previously issued to
Berdan's Sharpshooters and were equipped with 371/2" barrels.